This invention relates to the synthesis of polyurethane products obtained by the reaction of formulation(s) comprising polyol, polyisocyanate, and chain extender, in the presence of a flow modifier which is characterized by at least one urethane group, i.e., ##STR2## The reactants of choice such as in a two package system, e.g., the isocyanate materials in one package and the materials forming the second package, e.g., polyol(polyester polyol or polyether polyol), chain extender, blowing agents (organic and/or H.sub.2 O), cell regulation agent, etc., which may comprise this isocyanate-curable second package, can influence the kind of polyurethane product obtained as well as its over-all properties. Thus the polyurethane product can be, for instance, a dense elastomer or an integral skin microcellular elastomer or open cellular product and the like.
Plasticizers are widely used in polymer arts such as with polyvinyl chloride, chloroprene resins, acrylics, polyvinyl butyral, nitrile rubber, polyreuthanes, cellulosic products, and others. The plasticizer should be compatible with and not "sweat out" from the plasticized resin. Desirably the plasticizer should act as a processing aid during the formation of the resin or ultimate resinous article. The plasticizer should achieve the goals which dictated its use in the first place without detracting from the properties of the unplasticized resin.